Fan Sound Absorption

[ALothlórienTree]

Hi guys,

I need to absorb the sound of my 8" fan.

My thought was to house it in a plastic storage container and surround it with sound insulation. The internet's consensus seems to favor rockwool for sound insulation. Cheap and good performance.

It seems pretty straight forward but it's always helpful to see someone else do it first. I was hoping the DIY Link-O-Rama would satisfy my needs to that extent. If anyone wants to drop some knowledge on the subject or supply a link to a good thread it'd be much appreciated.

 

[flyer81]

Part of the equation is starting with a quiet fan to begin with. Try an Elicent. There are a few other good brands that are not coming to mind right now. Also, go with a larger fan then necessary. I have 8" ducts but I use nothing but 10" elicents and use a speed controller to turn them down. I get just as much air blowing but the fans themselves are relatively silent because they are not running at 100%.

Only then if it is still not quiet enough would I try insulating them to keep the sound down.

 

[the gnome]

since you already have a fan things you can do like use insulated ducting
if your mounted to the ceiling/wall and noise is amplified from that, hang it by bungee cords.
if its just the fan wrap it in insulation, put it in a box.
prodex is great for insulation and will aborsb DBs

use the search function for this forum, ive seen more than a few on sound control for fan noise

I 2nd what flyer81 said.
over size and put a speed controller on it.
my 1st fan was a 6" elicent 150B,
recommended came from a grower that said they were quiet and durable, as inlines fans go.
its been running nearly nonstop since may 2010

 

[ALothlórienTree]

Thanks guys, what kind of speed controller do you use?

I've had one in the past but it made a buzzing sound when it restricted the fan so I ended up not even using it. Does your speed controller make any noise when keeping the fan at less than 100%?

 

[Iffy]

Hi Folks,
Just my ten cents worth;
I hang all my fans from strong elastic and always attach ducting to a wall outlet by flexi hose. All this will cut down on vibrations/harmonics. I have boxed a 6" RVK L1 fan and filled it with acoustic expanding foam. Seems to work well but it also offers the opportunity to add sound proofing foam etc as the boxed shape makes this easier. Though I've done all this, the majority of the noise generated by fans is from the air movement itself. Its worth making sure bends are minimised and I use smooth walled ducting corners to assist the flow. Always use acoustic flexi ducting and build a box around long runs. Fill these boxes with acoustic insulation and once again you have nice rectangular surfaces to add acoustic foam if required. I have also layered 25mm acoustic foam against my side of the neighbour's walls. I also intent to box my whole chimney breast & fill that with acoustic rockwool and plan to lay 15mm acoustic foam down on the floor and board over that again.
Overkill? Maybe but it helps me sleep at night.
Stay safe & happy growing

 

[Sativa Dragon]

Try hanging it from bungee cords.

Peace

 

[Sativa Dragon]

Iffy beat me to it ha ha.

Thanks bro great minds think alike

Peace

 

[Sativa Dragon]

Thanks guys, what kind of speed controller do you use?

I've had one in the past but it made a buzzing sound when it restricted the fan so I ended up not even using it. Does your speed controller make any noise when keeping the fan at less than 100%?

The buzzing you heard was just your fan motor falling out of sync with the frequency of your supply, here it is 60Hz.

Peace

 

[ALothlórienTree]

Iffy: Nice post, you've obviously put some thought into keeping things quiet.

What exactly do you mean by acoustic expanding foam?

 

[ALothlórienTree]

Sativa Dragon: is there way to fix it?

 

[Iffy]

Iffy: Nice post, you've obviously put some thought into keeping things quiet.

What exactly do you mean by acoustic expanding foam?

I got it off Ebay mate. It's just expanding foam developed with acoustic properties. You have to buy the gun & cleaning solution and I did find it took over a week to expand fully, so make sure you cut a blow hole at the top!

 

[Sativa Dragon]

Sativa Dragon: is there way to fix it?

There is no getting around the sign wave of your power supply, however with what Iffy mentioned all the vibes and resonance can be eliminated through the use of sound deadening.

It is the same thing with ceiling fans when you adjust the speed you should be able to here the faint buzz of inductance fighting against itself.

Peace

 

[ALothlórienTree]

There is no getting around the sign wave of your power supply, however with what Iffy mentioned all the vibes and resonance can be eliminated through the use of sound deadening.

It is the same thing with ceiling fans when you adjust the speed you should be able to here the faint buzz of inductance fighting against itself.

Peace

Thanks Sativa

I found this product is sold at my local home depot for about $5 a can. It seems like it should work.. I'll be posting back here after I give it a try.

 

[the gnome]

be careful using great stuff, i was told it will off gas.
I used about 15 cans of it building my room in sept-oct.
but it cures out and is ok.

do search on it.